Former deputy prime minister Tim Fischer says an inquiry into Australia’s involvement in the Iraq war would only be useful if senior US officials could be called.

Mr Fischer, deputy prime minister to John Howard when the decision was made to join the US-led war in Iraq in 2003, said any inquiry would need input from the former US decision makers.

“If we could subpoena former vice-president Dick Cheney and former secretary of defence Donald Rumsfeld, then perhaps it would be worthwhile,” he said on Sky News.

The recent Chilcot inquiry into Britain’s involvement in the Iraq war has sparked calls for a similar inquiry in Australia, most recently from Labor MP Mike Kelly, a former army lawyer who served in Iraq.

“It’s not too late. In fact I think some distance now behind us will give us an even better perspective and better opportunity to do that analysis properly,” he told ABC television.

Deputy Prime Minister Barnaby Joyce said he wouldn’t support an inquiry into Australia’s Iraq war involvement.

“Deciding to rake over the coals there, I don’t know if that is going to be better than trying to make sure we deliver on our security needs as they stand today,” he said.

With calls for an Iraq war inquiry have come fresh calls for parliament to gain power to approve or reject any decision to go to war.

Labor senator Lisa Singh says this is too important to be left solely to the prime minister.

“Our parliamentarians are intelligent enough, sophisticated enough to work through a system that would work,” she said on ABC television.

The Australian Constitution doesn’t say who has power to declare war or deploy troops. In practice, that’s decided by the prime minister and cabinet.

Legislation requiring parliamentary approval of any decision to go to war has been a staple of the parliamentary notice paper since 1985 when the Australian Democrats introduced their Defence Amendment Bill.

Similar bills, requiring approval of both houses of parliament, have been introduced by the Greens but have never gained support of Labor or coalition governments.

The Greens are likely to introduce another such bill early this parliamentary sitting.

The Senate foreign affairs defence and trade committee examined a Greens bill in 2009-10, concluding it contained a number of deficiencies which needed to be addressed if this measure was to be brought forward again.

Mr Joyce said such decisions needed to be made in a secure environment.

“They have to be made in such a way that the enemy does not know what you are up to,” he said.

The banking industry has hit back at calls for a royal commission into the sector, saying it would send the wrong message to the world about the stability of Australian financial institutions.

Opposition Leader Bill Shorten has renewed his attack on the big four banks after they failed to pass on this week’s official interest rate cut by the Reserve Bank to its customers in full.

“The decision by the banks to hold back the rate cut from hard-working Australians does nothing to help their credibility,” he said.

Labor has repeatedly called for a royal commission in the wake of a string of financial scandals that have hit thousands of mum and dad investors.

But Australian Bankers’ Association chief executive Steven Munchenberg said a royal commission was unnecessary because the institutions were already dealing with the issues.

“It’s better for us to be fixing those problems now than waiting for some drawn out royal commission,” he told ABC radio.

ANZ, Commonwealth Bank, National Australia Bank and Westpac made only modest reductions to their standard variable mortgage rates of 0.10 per cent to 0.14 per cent compared with the Reserve Bank’s reduction of 0.25 per cent.

Prime Minister Malcolm Turnbull admonished the banks on Wednesday for not passing on the cut, demanding an explanation from the bank’s chief executives.

But Mr Shorten called Mr Turnbull’s “lecture” to the banks “weak and pathetic” and said confidence had been eroded in the system.

“Mr Turnbull will give the big banks another empty lecture and a tax cut. I’ll give the banks a royal commission.”

A former Reserve Bank board member backed the need for an inquiry into banks, insisting the quality of financial advice they provide needs to be examined more closely.

“Their authority in that area is becoming vastly bigger than it was even a decade ago, and I think that’s where we need to get a better idea of what the culture is and how good the performance and practice is,” John Edwards, who was economic adviser to former Labor Prime minister Paul Keating, told ABC TV.

Independent federal MP Andrew Wilkie said the central bank wanted to kick-start a slowing economy and the banks need to do their part.

“It’s not like they are scrapping for cash here, they are making enormous profits and should pass (the rate cut) in full,” Mr Wilkie told Sky News.